Earth with large oceans, rivers and glaciers near the North and South poles, doesn’t seem to have a water shortage. But the fact is that she is 99-percent dry rock. Only less than 1 percent of its mass is water!
Astronomers have been puzzled by Earth’s water deficiency because of our current solar system formation model.
By observing how young stars behave, they found that our planet formed from rocky debris in a dry, hotter region, inside of the so-called “snow line.”
Snow line is the region within a planetary system beyond which temperatures are cold enough for water ice to exist. In our solar system is currently located in the middle of the main asteroid belt, between the orbits of Mars and Jupiter.
Previous accretion-disk models suggested that the snow line was much closer to the Sun 4.5 billion years ago, when Earth formed.
According to a study led astrophysicists Rebecca Martin and Mario Livio of the Space Telescope Science Institute in Baltimore, Md., Earth was never inside the line. Instead it was in a warmer region inside of the snow line.
“Unlike the standard accretion-disk model, the snow line in our analysis never migrates inside Earth’s orbit. Instead, it remains farther from the Sun than the orbit of Earth, which explains why our Earth is a dry planet. In fact, our model predicts that the other innermost planets, Mercury, Venus, and Mars, are also relatively dry, ” explains Mario Livio.